Tractor



FIG. 1 is a perspective view of a tractor showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The portions of the Figures shown in broken lines form no part of the claimed design. 

We claim the ornamental design for a tractor, as shown and described. 